It is known that the consumption of paper and cardboard is constantly and progressively increasing throughout the world and that there is an increasingly urgent need to resort to sources of supply for cellulose as raw material for paper manufacture other than those hitherto used traditionally, that is to say plants with a wooden stem such as conifers, broadwoods etc., also with consideration of the adverse environmental impact connected with the massive felling of forest trees.
For this reason, various studies of the possibilities of using annual plants such as wheat, sorghum, maize, hemp etc. in the production of cellulose have been carried out in recent years.
The major problem encountered with the use of annual plants in the production of cellulose is represented by their low density and consequently the enormous volumes of raw material which must be transported from the growing fields to the paper mills.
This entails such an increase in costs that, from an economic point of view, the use of annual plants as sources of cellulose is rendered unsuitable, which per se already give yields lower than those obtainable with the use of plants with a wooden stem, when they are worked according to the processes conventionally used in paper mills.
These latter are by themselves already characterized by a low profitability, since they are based on the use of now technologically obsolete equipment. Moreover, the equipment of conventional paper mills is necessarily of considerable size and involves very high installation costs.
The abovementioned problem of the high transport costs could be overcome by locating production units for the extraction of cellulose in the vicinity of the places where the plants are grown. However, because of the high investment required for the construction of a conventional paper mill plant, it would be difficult to propose locating a plurality of production units in the vicinity of places where the plants are grown.